While imaging part of a body of a human being, the amount of radiation emitted by the source and received by patients whose body is imaged as well as operators manipulating the imaging system, should be reduced. Therefore, to reduce the amount of radiation received by the patient, one efficient way is to limit the exposure of the anatomical part of body to be imaged.
Minimizing the amount of ionizing radiation used during x-ray guided interventional procedure is of importance to protect both patients and operators. Several strategies can be used as part of standard radiation protection practice. In particular, collimating the x-ray beam to limit exposure to the anatomical region being treated is very effective as it limits the x-ray beam to the required area. However, this comes at the expense of not being able to see the surrounding anatomical context. In addition, collimating to the right anatomical area requires operator action. This is the reason why collimation is often underutilized, thus leading to larger than necessary exposed area.
Currently, it is known to display one image showing at the same time the whole field of view of imaged zone as well as the more limited region of interest in the middle of the field of view. To be able to limit radiation exposure and frequently update information on the region of interest, the refreshing rate of the region of interest of the imaged zone is notably higher than the refreshing rate of the rest of the field of view surrounding the region of interest of the imaged zone.
However, even if satisfactory at first sight, this method has several drawbacks. When displaying the region of interest and field of view of an imaged zone in a single image on a single display window, the region of interest being within the center of field of view, choosing the size of the image to be displayed leads to a compromise. Either a limited size of displayed image is chosen or a big size of displayed image is chosen. If a limited size of displayed image is chosen, then the size of the displayed region of interest on the screen may be too small to be easily exploited by the operator. If a big size of displayed image is chosen, then the screen may be too cumbersome. Of course, a compromise can be chosen in between; but for the relatively big size of image, the size of the displayed region of interest on the screen may then appear as too narrow. Besides, in this method, the region of interest is not displayed in optimal conditions; indeed, the size of the displayed region of interest on the screen is too small.